1. Field of the Invention
The invention relates to an optical waveguide usable for optical interconnection, optical modulator, optical integrated circuits, optical switches, distributors, optical transmitter-receiver modules and the like and a device for optical communication using the optical waveguide.
2. Related Art
In the situation of recent advancement of broad-band for internet, in order to make access such as FTTH widely available, considerable cost down of devices for optical communication is urgent necessity. As a device for optical communication, an optical transmitter-receiver module for converting optical signals into electric signals is employed for a terminal device of an optical communication appliance. In order to miniaturize the optical transmitter-receiver module and lower its cost, a method for producing an optical waveguide, which is a part disposed in the module, from an organic polymer material is proposed (Nobuo MIYADERA, “Polymer Material for Optical Waveguide”, Optical Alliance, p. 13, 2, 1999).
For example, a lower clad layer is formed on a substrate and an optical transmission layer of an optical polymer material is formed on the lower clad layer. The optical transmission layer is formed by forming a pattern with RIE or UV radiation by employing photolithography and removing unnecessary parts. An upper clad layer is formed on the optical transmission layer formed in such a manner. In many cases, both of the lower clad layer and the upper clad layer are formed from organic polymer materials.
However, in the case the upper clad layer of the optical waveguide is formed from a material such as an organic-inorganic composite or a resin material which is shrunk in volume at the time of curing, the volume is shrunk at the time of upper clad layer formation and that is adverse consequence that the lower clad layer tends to be easily cracked or peeled.